Folding sheet material



Sept.r 17, 1935. T. c. RowN Y FOLDING SHEET MATERIAL` Filed April 27,1932 .Z/SheetS-Sheet 1 y WVM/TUR'.

@by-W n 17; 1935. `r. QROWEN 2,014,453

FOLDING SHEET MATERIAL Filed April 27, 1932 Y 2 Sheets-Sheet 2 7 Fl g;2Q

ioo f Thermal UnTs Patented Sept. 1 7, 1935 FOLDING SHEET. MATERIALIhomas C. owen, Swampscott, Mass., assigner to United Shoe MachineryCorporation, Paterson, N. J., a corporation of New Jersey ApplicationAppu 2r, 1932, semi No. 601,767

13 claims. (01. iz-ss) This invention relates to a method of folding themargin of a piece of sheet material .by the use of a cement whichisnormally not tacky but may be` rendered tacky by the application of a5 suitable agent and to a folding machine equipped -to handle work whichhas a coat of this sort of cement.

Inthe manufacture of the uppers of boots and shoes it is customary tofold certain margins of the shoe parts in order to produce smoothlyfinished edges thereon. Two procedures are in common-use. In the rst themargin of the shoe part vis-skive'd, a coating of cement is applied tothe margin, and then the margin is foldedover upon .the body portion'.In the second a narrow binding strip-usually of fabric-is sewed along an`edge of the shoe part, said strip -being provided,`

either before or after itsV attachment, with a coat of cement, and thenthe free portion of the 20. binding is folded over upon the sheetmaterial. Thus in both cases the cement'acoated margin ofva piece ofworkis folded over upon the body portionv thereof. vIt has been proposedto use a cement which' is normally non-sticky but is 25, adapted tobecome sticky upon being treated with a suitable softening agent, forexample heat; and the present invention relates to the folding of sheetmaterial with the use of a cement of this kind which is normallynon-sticky. .i0 YIt is desirable to strengthen the work at or adjacentto its vfolded edge by the application of a strengthening member such asa piece of tape; and in one aspect the invention comprises a method inwhich there is directed upon the body' portion of a piece of work havinga coating of thermoplastic cement upon a margin thereof, a piece of tapehaving a similar coating, progressively softening the two coatings andprogressively pressing the tape. upon the workand fold- 40 .ing themargin of the work. As herein illustrated, the tape is pressed upon thebody /portion of the work close to the cemented margin thereof, thesoftening is accomplished by a blast of hot gas, and the margin isfolded over upon the tape.

Hitheito mechanisms embodied in folding machines -for producing hot gasand directing it uponthe work have comprised an electric heat unitprovided with a rheostat for varying its temperature, a blower or fan,and a conduit leading from `the blowe past the heat unit to a nozzle.Such a blowe produces a constantcurrent of air at almost negligiblepressure; and consequently a heat unit of considerable capacity mustbeused. There is thus a comparatively slow of the slowly moving currentof air at the noz- 10A zle is diflicult. Moreoverpbecause of` thefactthat the nozzle must be pointed down upon the work and the movementof the current of air is comparatively slow, the ,hot air isl more orless dissipated instead of being all carried to the 15 work. In order toobviate these disadvantages there is4 provided, in combination withwork.- feedingand folding instrumentalities, anozzle, a

- constant source of heat, a positively acting pump for forcing gasunder substantial pressure past 2o the source of heat through thenozzle, and means `for Varying the pressure. In the illustrated machinethe source of heat is an electric heat unit through a. spiral passagearound which the air is forced, and the positively acting pump is one'25 capable of producing a pressure o f several pounds per square inch;With this construction in which a considerable pressure isrused, theamount of 'heat delivered to the work may be very delicately controlledby manipulating the reliei:` Valve to 8@ increase or decrease thepressure of the air, and practically all of the fast moving air deliverfrom the lnozzle reaches the work.

Referring now to the accompanying drawings, Fig'. 1 is an elevation of amachine by the use ci 85 which the method may be conveniently practiced.

a piece of work being. shown in process of being operated upon;

Fig. 2 is a detail principally i'n section oi the heating means;

f o Fig. 3 is a `chart showing the amounts of heat delivered at certainspeciiied pressures; and

Fig. 4 is a section on an enlarged scale showing a finished piece ofwork comprising a piece of leather having a piece of tape along one edgew -thereof and a strip of binding folded about the edge of the leatherand over upon the tape.

Referring first to Fig. 1 the folding machine comprises a base 5 adaptedto rest upon a bench and an arm IV having at its outer end a work sup-5o yport 9 over -which thework is fed.. The particular work shown ispart of the strap of `a ladies" pump and comprises a piece of leather|00 having attached to its margin a strip of fabric binding 200. On theleft hand ,side of the-work a piece of 55 tape 300 has been applied tothe leather or body sageway S1 in a cylindrical casing 39 mounted onportion of the work, and the binding has been folded over and presseddown upon the tape. On the right-hand side ofthe work, the tape 300 isbeing directed upon the leather, and the binding 2" is in process ofbeing folded.

As herein illustrated the tape 300 has a coating of thermoplastic cementon that face which, in the finished work, contacts with the leather;andthe binding 200 has a similar coat on that face which, in thenishedwork, contacts with the tape. A presser or creaser l I engages theedge of the leather and has a slot inclined downwardly in the directionof feed movement of the work through which the tape passes as it isdirected upon the margin of the leather. A slender guide il engages theedge of the leather, a folding finger, not shown, bends the bindingabout the edge of the leather, and a hammer I1, having a fourmotion feedmovement, presses the binding against the tape and the tape against the`leather and also acts to feed the work intermittently away from theobserver as viewed in Fig. 1. The tape 309 is fed in a suitable mannerfrom a reel, not shown, through a guide slot in a small bar I9,

and from there is directed upon the work and fed with the work by thehammer which, stated above, has a four-motionmovement. The small bar i9has a hole in its inner end to receive a threaded` stud 20 carried bythe frame of the machine and is held adjustably in position `by a clampnut 22.

'I'he folding machine, except for the tape guide, theedge guide Il andcertain changes in the shape of some of the work engaging parts is ormay be substantially the same as that shown in United states LettersPatent No. 1,702,598.

granted February 19, 1929 upon an application illed in the name ofPerley R. Glass and no further description of it will be given since thedetails of its construction form no partof the present invention and anysuitable folding machine may be used. It will be understood, however,that the work, including the tape, is fed intermittently away from theobserver, as viewed in Fig. 1, that the tape is progressivelyA directedupon the leather or body portion of the work, and that' l the binding ormargin of the work is progressively folded over and pressed upon thetape.

The tape and the binding each carry a coat of thermoplastic cement, thetape being coated on that face which will contact with the work, and the`binding being coated on that side which will contact with the upperuncoated face of the tape as it lies upon the work. In order to softenthese .coatings progressively there is provided a nozzle 2| so locatedas to direct a blast of hot air upon the coated side of the .tape andthe coated side of the binding simultaneously. This blast strikes thetape :lust before it enters the guiding groove in the presser foot H andstrikes the binding just before it passes this foot. This nozzle is fastto the lower end of a curved pipe 23, the upper end of which (Fig. 2) isfast to a nipple 2i which leads from a straight passageway 21 ln a em\ber 2l provided' with a hand wheel 2l an rotatably mounted in a sleeve3l, there being a conical, gas-tight, ground joint between these 'twomembers which are held from longitudinal movement with respect to' eachother by a compression spring 33 seated on' the end of the sleeve ll andengaging a nut Il threaded on the small end of the member 2l. Bymanipulating this hand wheel, the nozzle may beswung-up into inoperativeposition at any time. The passageway 'I1 communicates with one end of aspiral pas- .belt, not shown, which may be placed upon any the frame ofthe machine and having an electric 31 with the outlet of a positivelyacting air pump 5 45. I'his pump may be ofany suitable type which iscapable of producing a considerable pressure of air, the illustratedpump being a rotaryv one driven from any suitable source of power by a10 one of the three pulleys 49 on the driving shaft 5l. In order topermit the pressure to be varied while the pump is running, a pipe 53connected at its lower end to the outlet pipe 43, has its upper endclosed by a relief valve 55 held down by a compression spring 51 thetension of which may be varied by turning an adjusting nut 59.

The possibilities of an apparatus of this type appear in the chart shownin Fig. 3, which shows graphically the results obtained by the use of a20 heat unit of watts and pressures from about two ounces to fourpounds. The curve of the graph would, of course,- vary somewhat inaccordance with the construction of the apparatus and the nature of thematerials used but the 25 graph shows in general what occurs. Thevertical column of iigures represents thermal units, that is thetemperature of th air just outside the nozzle, 'multiplied by the volumeof air passing ,through the nozzle per second. The horizontal line "offigures represents the pressure of air at the nozzle in pounds persquare inch.' It will be noted that the thermal units delivered by thenozzley increase vry rapidly with increase inl pressure up to one-halfpound pressure and continue to increase although less rapidly up to fourpounds pressure. With the particular apparatus from which this chart wasmade and with a piece of work coated with a commonly used commercialthermoplastic cement, a pressure of one 4o pound was found to result ina proper softening ofl the cement.

The 4hot air delivered to the work has a tendency to heat undesirablyadjacent portions of the machine; and in'order, to withdraw some of 45this hot air from the locality adjacent to the work, a suction pipe 6Iwhich leads to the inlet of th'e pump has its intake vopening Il locatedto withdraw hot air which may collect in the neighborhood of thework-engaging parts of the 5o machine. 'This withdrawal of hot air notonly prevents undesirable heating of the work-engaging parts of themachine, vbut carries back tothe pump air which is already somewhat warmand will require less expenditure of heat to raise it 55 again to thedesired temperature.

Although the tape has been shown and described as being directedinto-such a position on the work that the margin of the work is" foldedover upon it, it should-be understood that a0 the invention is notlimited to this particular location of the tape, and although theillustrated claim as new andl desire to secure by Letters 7o I Patent ofthe United States is:

1. The method of folding a piece of sheet material having upon a marginthereof a coat-of thermoplastic 'cement and at the same time saidmaterial which comprises I5v progressively directing upon the bodyportion of the sheet material a separate piece'of tape having on thatside which will be in contactv with the sheet material a coat ofthermoplastic cement, progressively heating the two coats of cementsimultaneously while the tape and the margin are in separated relation,and thereafter progressively pressing the tape against the sheetmaterial and folding the margin.

2. The method of folding a piece of sheet material having upon a marginthereof a coat of j terial having upon a margin thereof acoat .of

thermoplastic cement which comprises progressively directing upon thebody portion of the sheet material a separate piece of tape having onthat side which will be in contact with the' sheet material a coat ofthermoplastic cement, v

thereafter progressively folding the margin over .upon the tape, andprogressively heating the two coats of cement prior to the foldingoperation.

4. The method of folding a piece of sheet material having upon a marginthereof a coat of thermoplastic .cement which comprises progressivelydirecting upon the body portion of the sheet material a separate pieceof tape having on that side which will be in contact with the sheetmaterial a coat of thermoplastic. cement, thereafter progressivelyfolding the margin over upon the tape, and directing a blast of hot gasupon the two, coats of cement to soften them prior to the foldingoperation.

5. The method of folding a piece of work which comprises a piece ofsheet material to which a strip of binding coated with thermoplasticcement is attached which comprises progressively directing upon themargin of the sheet material a piece of tape coated with thermoplasticcement on the side which is to contact with the piece of sheet material,progressively heating the cement on the binding and on the tape, andprogressively folding the binding over upon the tape. 6. The method offolding a piece of work which comprises a .piece of sheet material 4towhich a lstrip of binding coated with thermoplastic cement is attachedwhich comprises progressively directing upon the margin of the sheetmaterial a piece of tape coated with thermoplasticcement on the sidewhich is to contact rwith the piece of sheet material, progressivelydirecting a blast of, hot gas upon the cement on the binding and on thetape, and progressively folding the binding over upon the tape.

7. A machine of the class described having, in combination, a supportover which a piece of work is fed, means for folding the margin thereof,means for directing upon the work prior to the folding operation a pieceof tape having a coating of hard thermoplastic cement thereon, andmeansfor directing upon the tape before it reaches the work a blast of notair to' soften the cement.

8. A machine of the class described having, in combination, a supportover which a piece of work having a coating of thermoplastic cement 5 onthe margin thereof is fed, means for folding the marginal portion of thework over upon the body portion and for pressing the folded-over marginagainst the body portion, means for directing a blast of hot gas uponthe work prior to the completion of the fold to cause the cement to besoftened, and means for withdrawing heated gas from the locality inwhich it is delivered by the nozzle to avoid undesirable heating of thework engaging parts of the machine.

9. A machine of the class described having, in combination, a supportfoi` a piece of sheet material having upon a margin thereof a coat ofthermoplastic cement, means for feeding the sheet material over thesupport, means for directing 20,

upon the body portion of the sheet material a piece of tape having acoating of thermoplastic cement on one side thereof, means for softeningthe coats `vof cement on the tape and on the-margin of the material, andmeans for pressing the tape against the body of the sheet material andfor folding the margin of said material.

10. A machine of the class described having, in combination, a supportfor a piece of sheet material having upon a margin thereof a coat ofthermoplastic cement, means for feeding the sheet material over thesupport, means for directing upon the body portion of the sheet materiala piece of' tape having a coating of thermoplastlc cement on one sidethereof, means$5 lfor softening the coats of cement on the tape and onthe margin of the material, and means for y folding themargin over uponthe tape.

11.-A machine'of the class described having, in combination, a supportfor a piece of sheet40 Vmaterial having upon a margin thereof a coat ofthermoplastic cement, means for feeding the material over thesuppnrtmeans for directing upon the she'et material a piece of tapehaving a coating of thermoplastic cement on one side thereof, 45

. means for directing upon the two coats a blast of hot gas tosOften'them, and means for pressing the tape against the body portion ofthe sheet material and for f olding the margin.

12. A machine of the class describedhaving, in combination, a supportfor a piece of sheet material having upon a margin thereof a coat ofthermoplastic cement, means for feeding the material over the support,means for 'directing-upon the sheet material a piece of tape-having acoating of thermoplastic cement on one side'thereof, means for directingupon the two coats a blast of hot'gas to soften them, and means forfolding the margin over upon the tape. y

13. A macmnevof the dass described having,

in combination, a support over which a pieceof work is fed, means forfolding the margin of the work, means for directing upon the work alonga f lpath substantially parallel with the edge of the Awork to underliethe folded margin thereof and prior to the folding operation a piece' oftape having a coating of hard thermoplastic cement thereon, and meansfor heating and softening the', cement prior to the completion of thefolding operation. f 70 THOMAS C.' ROWEN.

